Em4885 irrigation management practices to protect ground water

1 CHAPTER
Purpose
INTRODUCTION
This document is titled Irrigation Management Practices to Protect Ground Water and Surface
Water Quality - State of Washington. It will be referred to as “the Manual.”
The primary purpose of the Manual is to present a series of Overall Management Objectives
(Objectives) for irrigated agriculture in Washington. The primary audience for the Manual is
intended to be farm operators and their advisors. The Objectives address the problem of nonpoint
source pollution from practices associated with irrigated agriculture. The Objectives will, if achieved,
help to control nonpoint source pollution of ground and surface waters. It is the responsibility of the
individual farm operator to achieve these Objectives under the current state and federal strategies of
voluntary action for controlling nonpoint source pollution.
A series of Implementation Practices (Practices) is listed for each Objective to help achieve
that Objective. The Practices are functionally equivalent to what have been generally termed Best
Management Practices. The Practices address changes to both management and facilities for control
of nonpoint source pollution.
It is important to realize that science is not static. The Objectives and Practices listed in the
Manual are generally recognized to be effective in reducing the potential for point and nonpoint
source pollution. However, there may be other Practices not presented in the Manual that are also
effective. And, science and practical experience will develop new Practices in the future. The
Manual is a “living” document; Objectives and Practices will be updated periodically.
Nonpoint source pollution as defined by the Federal Environmental Protection Agency
is “. . . pollution . . . caused by diffuse sources that are not regulated as point sources. . . .”
Further, the Washington Legislature has defined nonpoint source pollution as “pollution
that enters the waters of the state from any dispersed water-based or land-use activities,
including, but not limited to, atmospheric deposition, surface water runoff from agricultural
lands, urban areas, and forest lands, subsurface or underground sources, and discharges
from boats or other marine vessels.”
Nonpoint source pollution is cumulative in nature. While any source of nonpoint source
contamination may be insignificant, the cumulative effect of many such sources is measurable
and leads to significant pollution of ground or surface waters.
It is difficult, by its nature, to assign responsibility for nonpoint source pollution when it occurs.
Nonpoint source pollution is usually the result of land-use activities. Thus, modifying land-use
activities can reduce or control nonpoint source pollution. The current state and federal strategies for
reducing and controlling nonpoint source pollution rest heavily on education and voluntary adaptation
of those actions which reduce the potential for pollution. The Manual provides education as well as
lists of possible practices to help farm operators take those voluntary actions that can reduce and
control nonpoint source pollution from irrigated agriculture.
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